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Abstract:

A system and a method to protect an image on a substrate. The method
includes applying a coating to the surface of a substrate having an
unspread ink image thereon, wherein the image is formed by droplets of
solid ink, and wherein the coating interacts with the ink. Moreover, the
method includes spreading the coated ink on the surface of the substrate,
wherein the ink and the coating interact during the spreading process and
wherein the spread ink on the surface of the substrate forms the
continuous image.

Claims:

1. A system for protecting an image on a substrate, the system
comprising:an ink delivery station, wherein the surface of the substrate
is printable by ink from the ink delivery station, wherein the ink from
the ink delivery station is applied direct to paper and is in an unspread
condition; anda coating station, wherein a coating from the coating
station is applied to the ink in the unspread condition, wherein the
coating interacts with the ink as the ink on the substrate changes from
the unspread condition to a spread condition, and wherein the ink in the
spread condition forms the image.

2. The system according to claim 1, further comprising:a glosser, wherein
the coating station is positioned between the glosser and the ink
delivery station, wherein the glosser changes the ink from the unspread
condition to the spread condition.

3. The system according to claim 2, further comprising:a mid-heater
positioned between the coating station and the glosser, wherein the
mid-heater heats the substrate and/or dries the coating.

4. The system according to claim 1, wherein the coating is an
aqueous-based coating.

5. An image forming apparatus including therein the system of claim 1.

6. A method for protecting a print comprised of ink, the method
comprising:applying a coating to ink printed on a surface of a substrate,
wherein the ink on the surface of the substrate is in an unspread
condition; andinteracting the coating and the ink as the ink changes from
the unspread condition to a spread condition, and wherein the ink in the
spread condition forms the image for the print.

7. The method according to claim 6, wherein the interacting comprises
applying pressure to the ink, wherein the pressure moves the ink to the
spread condition.

8. The method according to claim 6, wherein the interacting comprises
applying heat to the substrate before the ink is in the spread condition.

9. The method according to claim 6, wherein the coating is an
aqueous-based mixture.

10. The method according to claim 6, wherein the interacting
comprises:moving the substrate with the coating to a glosser, wherein the
glosser bonds the coating to the ink and/or the substrate.

11. The method according to claim 6, wherein interaction between the ink
and the coating strengthens the ink and coating against removal from the
surface of the substrate.

12. The method according to claim 6, wherein the interacting
comprises:moving the substrate with the spread ink and coating to a
mid-heater, wherein the mid-heater heats the substrate and/or dries the
coating.

13. A method for protecting an image on a substrate, the method
comprising:applying droplets of ink onto a surface of a substrate in an
image configuration;applying a coating to the surface of the substrate
having the ink thereon; andspreading the ink on the surface of the
substrate, wherein the ink and the coating interact during spreading of
the ink, and wherein, after spreading, the ink on the surface of the
substrate forms the image.

14. The method according to claim 13, further comprising:moving the
substrate with the spread ink and coating to a mid-heater, wherein the
mid-heater heats the substrate and/or dries the coating.

15. The method according to claim 13, further comprising:applying pressure
to the ink on the substrate with the coating thereon, wherein the
pressure increases interaction between the ink and the coating.

16. The method according to claim 13, wherein the coating is an
aqueous-based mixture.

17. The method according to claim 13, further comprising:interacting the
ink and the coating by means of a spreader, wherein the spreader moves
the ink from an unspread condition to a spread condition.

18. The method according to claim 13, wherein interaction between the ink
and the coating strengthens the ink and coating against removal from the
surface of the substrate.

19. The method according to claim 13, wherein the ink is solid ink.

Description:

TECHNICAL FIELD

[0001]This disclosure is directed to a system and a method for forming a
robust print. More particularly, in embodiments, this disclosure is
directed to a coating that is applied to the surface of a substrate with
a direct to paper ink image thereon. The coating may be applied to the
surface of the substrate after an ink jet printer has printed the image
but prior to ink spreading of the image on the surface.

[0002]The interaction between the coating and ink during the ink spreading
process may increase durability, permanency and consistency of the image
formed on the surface of the substrate. As a result, robustness of the
image may be improved by the increased interaction between the coating
and the ink and damage caused from a force of movement such as rubbing,
creasing, scratching and the like may be reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0003]Disclosed in commonly assigned U.S. patent application Ser. No.
11/421,299, filed May 31, 2006, is a recording medium with an ink image
thereon, wherein a varnish at least partially covers the ink image, and
wherein the varnish composition prior to application comprises at least
one latex emulsion, water, at least one base and at least one surfactant.

[0004]The entire disclosure of the above-mentioned application is totally
incorporated herein by reference.

BACKGROUND

[0005]An ink jet printer generates prints or images by transferring ink
from ink jet heads to a substrate, such as coated paper stock or uncoated
paper stock. One type of ink used in ink jet printers is a solid, or
phase change, ink. In some cases, such ink images may be rubbed or
scratched from the surface of a substrate by minimal force; for example,
due to poor bonding between the ink and the surface of the substrate. A
movement, such as rubbing, scratching or creasing of the ink on the
substrate may exert sufficient force on the ink to separate the ink from
the surface of the substrate.

[0006]A coating may be applied to the surface of the substrate, with a
spread ink image thereon, to cover the surface during a finishing step.
The coating covers the surface of the substrate to protect the ink of the
image from being rubbed from or scratched from the surface of the
substrate. The coating may be a continuous dry film that is formed over
the ink of the image. However, by applying the coating as a finishing
step, the coating may not bond sufficiently with the ink on the surface
of the substrate because the coating may fail to interact with the ink.
As a result, the coating may be removed from the surface of the substrate
by rubbing, scratching or creasing, while the ink may remain on the
substrate.

[0007]Because the coating typically covers the entire surface of the
substrate, the coating may often enhance the gloss of the surface, which
may increase the visual appeal of the print or image. However, the poor
interaction between the coating and the ink may allow the coating to be
easily removed from the substrate. As the coating is removed from the
surface of the substrate, the continuous film formed by the coating may
become non-uniform or non-continuous across the surface of the substrate.
As a result, the coating removed from the surface may form one or more
visual detects to the gloss or to the continuous film.

[0008]Therefore, a need exists for a system and a method for protecting an
ink image on the surface of a substrate that may apply a coating to the
surface of the substrate prior to ink spreading of an image.
Additionally, a need exists for a system and a method for protecting an
ink image with a coating that may increase the strength of the
interaction between the ink and the coating, thereby improving the
robustness of the print. Further, a need exists for a system and a method
that may apply heat and/or pressure to the ink and coating for increased
interaction. Moreover, a need exists for a system and a method that
provides a coating to minimize damaging effects to the image caused by a
force such as rubbing, scratching and creasing.

SUMMARY

[0009]The present disclosure addresses these and other needs, by providing
a system and method for protecting a print. The system includes an ink
delivery station, wherein the surface of the substrate is printable by
ink from the ink delivery station, wherein the ink from the ink delivery
station is in an unspread condition. Moreover, the system includes a
coating station, wherein a coating from the coating station is applied to
the image in the unspread condition. The coating interacts with the ink
as the ink on the substrate changes from the unspread condition to a
spread condition.

[0010]The method includes applying a coating to ink printed on the surface
of a substrate, wherein the ink on the surface of the substrate is in an
unspread condition. Moreover, the method includes bonding the coating and
the ink as the ink changes from the unspread condition to a spread
condition, wherein the ink in the spread condition forms the continuous
image for the print. The interaction between the ink and coating prevents
the ink or the coating from being removed from the surface of the
substrate.

[0011]In embodiments, provided is a method for protecting a print. The
method includes applying a coating to the surface of a substrate having
an ink image thereon, wherein the image is formed by droplets of solid
ink. Moreover, the method includes spreading the ink on the surface of
the substrate, wherein the ink and the coating interact during the
spreading of the ink.

[0012]Therefore, it is an advantage of the various embodiments described
herein to provide a system and a method for protecting a print formed by
an ink jet printer. The system and the method may have a coating that is
applied to the image prior to spreading of the ink. Another advantage of
the various embodiments is to provide a system and a method for
protecting a print formed with ink that may utilize heat and/or pressure
to increase the interaction between the ink and the coating. Yet another
advantage of the various embodiments is to provide a system and a method
for protecting a print that may, partially or entirely, apply a coating
to the print after ink jetting an image but before spreading of the ink
image. A further advantage of the various embodiments is to provide a
system and a method for protecting a print that may increase durability,
image permanence and robustness. Moreover, another advantage of the
various embodiments is to provide a system and a method for protecting a
print that may apply a coating to the print by a contact mechanism or a
non-contact mechanism.

BRIEF DESCRIPTION OF THE DRAWING

[0013]The FIGURE illustrates an example system for protecting a print in
an embodiment of the present disclosure.

EMBODIMENTS

[0014]As used herein, an ink spreading process refers to a process of
moving ink in an unspread condition to a spread condition via ink
spreading. For example, an ink spreading process may be a two roll nip
formation that uses temperature and/or pressure to enlarge the solid ink
drops on the surface of the substrate such that the spread solid ink
drops overlap each other. Ink in an unspread condition refers to solid
ink drops emitted onto the substrate that may not overlay each other and
may not be uniform and/or continuous across the surface of the substrate.
Ink in a spread condition refers to solid ink drops on the surface of the
substrate that may have been enlarged to be uniform or continuous across
the surface of the substrate and/or so that the solid ink drops overlay
each other.

[0015]In various exemplary embodiments, there is provided a system and a
method for protecting a print that may be formed on the surface of a
substrate. The print may be an image that may be formed by ink from an
ink jet printer. A coating may be applied to the surface of the substrate
to cover and to protect the image from being removed from the substrate
during rubbing, creasing or scratching. The coating is applied after the
ink is jetted onto the surface of the substrate from an ink delivery
station of the ink jet printer, but before the ink on the surface is
exposed to a mid-heater, a glosser, a spreader or the like. The coating
on the surface of the substrate may be exposed to heat and/or pressure
during the ink spreading process by the glosser or the spreader. The
interaction between the coating and the ink may prevent the ink and/or
the coating from being removed from the surface of the substrate by the
force from rubbing, scratching or creasing the image. As a result,
application of the coating prior to spreading the ink may increase
robustness and durability of the print, and may reduce visual defects of
the print.

[0016]In embodiments, the substrate may be made from paper, such as coated
paper stock, uncoated paper stock or any suitable coatable material. In
embodiments, "substrate" may refer to or may include other substrates,
such as transparencies, plastics and the like. In embodiments, the
substrate may be fabricated with a pre-coating, such as a gloss that may
cover a first side and/or a second side (collectively referred to
hereinafter as "the sides") of the substrate. Ink may be applied to or
may be printed onto one (simplex) or both (duplex) sides of the substrate
to form an image on the sides of the substrate. In embodiments, the
coating may be applied to or may cover the first side of the substrate to
protect the image on the first side of the substrate. In embodiments, the
coating may be applied to or may cover both of the sides of the substrate
to protect a double-sided print having an image formed on each of the
sides of the substrate. The coating may also cover only one or more
portions of either side of the substrate.

[0017]In embodiments, the ink that is transferred to the substrate to form
the image thereon may be, for example a liquid ink that is jetted onto
the sides of the substrate. The ink may be, for example a solid ink or a
phase change ink that may require heating to an elevated temperature
prior to jetting onto the substrate. At the elevated temperature, the
solid ink or the phase change ink may be converted into a liquid ink that
is capable of being applied to the substrate via jetting or the like. It
should be understood that the ink may be any suitable solid ink or phase
change ink that is convertible to liquid ink at an elevated temperature
for applying to the sides of the substrate.

[0018]Referring now to the drawing wherein like numerals refer to like
parts, the FIGURE illustrates a system 10 for printing an image onto at
least one of the sides of the substrate. In embodiments, the system 10 is
an ink jet printer system such as, for example, a solid ink jet printer
or the like. The system 10 may print or may transfer ink onto sides of
the substrate via a direct-to-paper (hereinafter "DTP"), or direct to
substrate printing operation.

[0019]In embodiments, the substrate may be, for example a reel of paper to
be processed by the ink jet printer of the system 10. In embodiments, the
substrate may be individual sheets of paper that may be fed singularly
into the system 10 from a feed supply tray or the like. The paper web or
individual sheets of paper may travel through or within the system 10
along a path 12 as shown in the FIGURE. In embodiments, the paper may
move or may travel in rightward motion from a first position adjacent to
the unwinder 14 through the ink jet printer to a second position beyond
to the glosser 16. In embodiments, the system 10 may include a dirt
abatement mechanism 18, a pre-heater 20, an imaging device 22 and an ink
delivery station 24 for transferring ink onto the substrate to form one
or more images of the print on the substrate. In embodiments, the system
10 may have tension rolls 26, an image sensor 28, a coating station 34,
mid-heaters 36 and a glosser 38 for spreading ink on the substrate and
for protecting one or more images formed thereon with a coating.

[0020]For supply rolls, the unwinder 14 unrolls the substrate. The
substrate may be moved to the dirt abatement mechanism 18 to clean dirt,
debris and the like from the sides of the substrate. The dirt abatement
mechanism 18 may have an air source 19a and/or a sticky roll 19b to
remove the dirt and the debris from the sides of the substrate via air
and/or an adhesive, respectively. The substrate may be moved to the
preheater 20, and may be exposed to heat emitted from the preheater 20
for preparing the substrate to receive ink thereon.

[0021]The substrate may be moved to a position adjacent to the ink
delivery station 22 along path 12 for receiving ink from one or more
heads 30a-30d of the ink delivery station 22. The heads 30a-30d may apply
or may transfer ink of one or more colors to the sides of the substrate
to print an image. The imaging device 24 may have electronics that are
programmed to control the heads 30a-30d for applying ink of one or more
colors onto the substrate to form the image.

[0022]Backup rolls 32a-32d may maintain the substrate in a position
adjacent to the heads 30a-30d, respectively. Ink from one or more of the
heads 30a-30d may be transferred to the sides of the substrate, and may
form the image of the print on the sides of the substrate. As a result,
ink from one or more of the heads 30a-30d may form one or more images
that may be a single-colored image or a multi-colored image.

[0023]In embodiments, one or more of the heads 30a-30d may spray molten or
melted solid ink directly onto the sides of the substrate in small
droplets to form the image on the substrate. However, the image formed by
the small droplets may not be a continuous image because a portion of the
small droplets of solid ink may not overlap each other. The small
droplets of solid ink may require spreading to expand and overlap each
other to form an image that is continuous on the substrate. Additionally,
the small droplets may require heating along with the spreading to
increase expansion and to form the continuous image.

[0024]The substrate may move along the path 12 past tension rolls 26 to a
position adjacent to image sensor 28 to detect defects in the one or more
images formed on the substrate. In embodiments, the image sensor 28 may
determine whether the image is accurately printed. It should be
understood that the images may be printed on the substrate by any ink jet
printing process or any DTP printing operation as known to one of
ordinary skill in the art.

[0025]The substrate may be moved to a position adjacent to the coating
station 34. The coating station 34 may be located between the ink
delivery station 34 and the mid-heaters 36 or may be located downstream
with respect to the ink delivery station 34. The coating station 34 may
apply or may transfer a coating onto the side(s) of the substrate after
the DTP printing operation of the ink delivery station 24 has printed ink
onto the side(s) of the substrate. In embodiments, application of the
coating by the coating station 34 to the side(s) of the substrate may be
identified as a pre-finishing step within a continuous solid ink jet
print process. "Pre-finishing step" refers to a step in a print process
which may be completed prior to exposing ink on the substrate to an ink
spreading device or ink spreading procedure.

[0026]In embodiments, the coating may be an aqueous-based coating, such as
the varnish as set forth above and disclosed in previously incorporated
U.S. patent application Ser. No. 11/421,299, or any commercially
available aqueous coating. In embodiments, the coating may permit
simplex/duplex coating for deposition of the coating on the substrate via
a gravure method or an offset gravure method. The coating may be, for
example, a water-based acrylic coating or the like. In embodiments, the
coating may be made of a composition containing ammonium hydroxide,
propylene glycol, carbitol, acrylic acid and/or styrene. It should be
understood that the coating may be any coating known to one skilled in
the art that may dry over a broad temperature range and which forms a
film over the ink.

[0027]The coating station 34 may utilize a contact mechanism or a
non-contact mechanism for applying the coating onto the sides of the
substrate. The coating may be applied to the sides of the substrate by
the coating station 34 via a coating method, such as, for example the
gravure method, the offset gravure method, a kiss roll method, a spray
method or the like. The present disclosure should not be deemed limited
to a specific embodiment of the coating method utilized by the coating
station 34 of the system 10. The coating station 34 may apply the coating
onto the sides of the substrate having the ink or the image that is
unspread. That is, the coating is desirably applied to surface of the
substrate having an ink image thereon prior to ink spreading of the
image.

[0028]The substrate may be moved to a position adjacent to the mid-heaters
36. The substrate and the coating may be exposed to heat emitted from the
mid-heaters 36 to heat the ink, coating and substrate prior to submitting
the substrate to the glosser 16. As a result, the heat from the
mid-heaters 36 may initiate drying and reduce moisture within the coating
as well as the ink and substrate which is covered by the coating. The
heat applied to the substrate by the mid-heaters 36 may increase
interaction between the ink and the coating. As a result, the coating may
begin interacting with the ink, and may begin to dry as the substrate
moves past the mid-heaters 36. In embodiments, the interaction between
the coating and the ink may refer to a mixing and/or a bonding between
the coating and the ink that may be initiated by heat and/or pressure
that may be applied to the substrate as the substrate pass through the
system 10.

[0029]In embodiments, the mid-heaters 36 may include infrared heaters for
exposing the substrate, ink and coating to heat. The substrate passes
through the infrared of the mid-heaters 36 for drying of the coating on
the substrate. As a result, the dried coating on the substrate may have a
coating thickness suitable to cover the unspread sample image with the
dried coating.

[0030]The substrate may move from the mid-heaters 36 to a position
adjacent to the glosser 16 for spreading of the small droplets of solid
ink and coating on the substrate. In embodiments, "glosser" refers to a
spreader that may apply pressure and/or heat to the ink droplets to
spread the ink droplets to form the continuous image. The coating may be
applied to the substrate and may cover a non-continuous image formed by
the small droplets of solid ink that have not yet been spread. The
coating and the ink may interact on the surface of the substrate during
the spreading by the glosser 16.

[0031]The glosser 16 may apply heat and/or pressure to the substrate for
spreading the small droplets of solid ink on the substrate. The glosser
16 may have rollers for exerting pressure onto the substrate as the
substrate passes through the glosser 16 and between the rollers. In
embodiments, the heat applied to the substrate by the glosser 16 may be
in a range of about 40° C. to about 70° C. and more
specifically in a range of about 50° C. to about 60° C. In
embodiments, the pressure applied to the substrate by the glosser 16 may
be in a range of about 750 psi to about 1,000 psi and more specifically
in a range of about 750 psi to about 850 psi.

[0032]The heat and/or the pressure applied by the glosser 16 may be
applied to the small droplets of solid ink on the substrate. As a result,
the glosser 16 may spread the small droplets of solid ink on the
substrate to form a continuous or final image for the print. The pressure
applied to the small droplets may cause the small droplets to expand and
to overlap each other to form the continuous image of the print on the
sides of the substrate. The heat applied to the small droplets may
increase expansion of the droplets from the applied pressure. As a
result, the small droplets may be spread and may form the continuous
image of the print on the substrate.

[0033]The heat and/or the pressure applied to the substrate by the glosser
16 may soften the ink and/or the coating on the substrate. A softening of
the ink and/or the coating may encourage or may permit interaction
between the ink and the coating thereon. With the ink and/or the coating
in a softened state, the glosser 16 may press or may mix the ink and the
coating causing interaction between the coating and the ink. As a result,
a strong interaction between the coating and the ink may be formed as the
substrate passes through the glosser 16.

[0034]The interaction between the coating and the ink may be strong enough
to prevent the coating from being separated or removed from the ink by a
force from scratching, rubbing or creasing. Force may be applied to the
image having the ink and the coating by a user, an object or the like. As
a result, the bond between the ink and the coating may improve or may
increase robustness of the image by preventing the ink and/or the coating
from being removed by the force from scratching, rubbing or creasing. In
embodiments, the coating may form a layer over the ink which is on the
substrate. In embodiments, the coating and the ink may meld together to
form a hybrid composition during the spreading process by the glosser 16.
As a result, the hybrid composition may be bonded to the substrate during
the spreading process.

[0035]Additionally, the ink and the coating in the softened state may
interact with the substrate and may bond with the substrate. The
interaction between the substrate, ink and coating may prevent the ink or
the coating from being removed from the substrate via the force from
rubbing, scratching or creasing the paper. With strong bonding between
the substrate, the ink and the coating, the force may not be great enough
to separate the coating from the ink or the substrate. As a result, the
bonding between the coating and the ink or the substrate may protect the
continuous image of the print on the substrate.

[0036]By applying the coating to the substrate prior to passing the
substrate through the glosser 16, the coating interacts with the ink
while being exposed to pressure and/or heat during passage through the
glosser 16. This interaction between the ink and the coating may
encourage a strong interaction between the coating and the ink which
allows the coating to protect the ink from being rubbed or scratched off
the substrate by minimal force. Thus, by applying the coating during a
pre-finishing step, such as prior to exposing the substrate to the
mid-heaters 36, the coating improves the durability, permanency and
quality of the continuous image of the print on the substrate.
Additionally, the coating may form a gloss over the continuous image that
may enhance the visual appeal of the print, and may reduce formation of
visual defects caused by removal of the coating from one or more portions
of the continuous image.

[0037]The substrate may be moved from the glosser 16 to a position beyond
the glosser 16. The image on the sides of the substrate may be continuous
after the ink droplets are spread by the glosser 16. Further, the heat
emitted from the glosser 16 may dry the solid ink and the coating for the
continuous image on the sides of the substrate. As a result, after the
substrate moves from the glosser 16, the continuous image of the print
displayed on the substrate may be dried and protected by the coating.

EXAMPLE

[0038]Small droplets of solid ink were transferred from a low energy solid
ink jet printer to a substrate, such as a piece of uncoated paper stock
having a basis weight of about 75 gsm. The small droplets of solid ink on
the substrate formed an unspread sample print by a DTP printing operation
of the low energy solid ink jet printer. For coating, the substrate
including an unspread sample print which was attached to a lead sheet and
fed through a coater. The lead sheet, attached to the substrate having
the unspread sample print (hereinafter "the image"), was fed through the
coater at a speed of about 30 m/min. As a result, a film was formed on
the image by the coater with a gravure roll of about 140 lines per inch.

[0039]The coated image was then placed on a belt of a fusion UV system and
fed through the fusion UV system at a speed of about 60 ft/ml. As a
result, the image and the coating were allowed to dry with the heat
generated by a UV light of the fusion UV system. The heat generated by
the UV light was at a temperature of, for example about 54.4° C.
As a result, the dried coating had a coating thickness in a range of
about 1.5 microns to about 2 microns. This formation of the coating
provided sufficient wetting to allow for coating over the unspread sample
image formed by the solid ink jet printer.

[0040]The unspread sample print including the dried coating was positioned
within the solid ink jet printer to allow for spreading of the sample
print. After spreading, the spread sample print with the coating
(hereinafter "Sample 1") did not exhibit an offset of either ink or
coating to a drum used for spreading Sample 1. An unspread sample print
(hereinafter "Comparative Sample 1") and a spread sample print with no
coating (hereinafter "Comparative Sample 2") were also created by the DTP
printing operation of the solid ink jet printer.

[0041]Scanning electron microscope images of Sample 1 and Comparative
Samples 1 and 2 were acquired and examined to determine performance
differences or structural differences. After reviewing the SEM images,
structurally it was seen that the coating and ink had melded together
during the coating process, as evidenced by the one continuous layer on
the substrate. Spreading of Sample 1 and Comparative Sample 2 was
substantially similar and no indications of picking or offset for Sample
1 were identified from the SEM images. With regards to performance, when
compared to a DTP print with no coating, the gloss was increased by about
approximately 10 gloss units (when measured at a 60 degree angle), rub
was decreased by about at least 50% and crease remained the same.

[0042]It will be appreciated that various of the above-disclosed and other
features and functions, or alternatives thereof, may be desirably
combined into many other different systems or applications. Also, various
presently unforeseen or unanticipated alternatives, modifications,
variations or improvements therein may be subsequently made by those
skilled in the art, and are also intended to be encompassed by the
following claims.

Patent applications by Christine D. Anderson, Hamilton CA

Patent applications by Gordon Sisler, St. Catharines CA

Patent applications by T. Brian Mcaneney, Burlington CA

Patent applications by XEROX CORPORATION

Patent applications in class Coating over the applied coating of particles

Patent applications in all subclasses Coating over the applied coating of particles